This application is copending with my other applications entitled "Drive System for a Track Type Vehicle" and "Idler Wheel Assembly".
The present invention relates generally to a drive wheel assembly, and more specifically to a drive wheel which includes at least one portion constructed of a material having a high coefficient of friction and a high degree of elasticity and another portion that has a sprocket of a fixed configuration.
Efforts are continually being made to improve the drive mechanisms for endless belts. A very positive form of driving an endless belt is by a sprocket engaging a series of openings equally spaced along the belt. The problem with such an arrangement includes excessive wear of the endless belt in the area of the openings. In order to overcome this problem endless belts have been developed with transversely extending reinforcement means which is embedded in the endless belt at the time it is constructed. This arrangement has the problem of heavy wear occurring at the sprocket when the endless belt is heavily loaded. This is in addition to wear occurring at the transversely extending reinforcements. One answer to this problem has been to limit the amount of penetration of the sprocket teeth into the openings. Again, there can be substantial wear of the sprocket teeth and of the reinforcing elements when the endless belt is heavily loaded and particularly if the arrangement is being used in an environment where abrasive contaminants may be introduced.
Power driven endless belts have been known for some time. However, none of the known systems teach a drive wheel assembly as taught by the instant invention. One prior art system, depicted in U.S. Pat. No. 3,120,409, shows an endless belt with V-belt type construction used in conjunction with integrally formed sprockets with V-grooves. The V-grooves of pulley 40 provide the primary driving forces and the sprocket teeth, with their engagement in openings in the belt providing the secondary, or backup, driving connection. Another endless belt assembly, depicted in U.S. Pat. No. 3,870,379, shows a flexible endless belt driven by a drive sprocket having teeth engaging in openings in the belt with a guide wheel disposed adjacent to the drive sprocket to prevent the flexible belt from engaging the sprocket teeth all the way down to the root. Another wheel and track assembly for a crawler type vehicle, depicted in U.S. Pat. No. 4,241,956, shows a drive wheel assembly having a sprocket 22 and includes cylindrical surfaces 88 for each cylinder 84 and 86 which is defined by an elastomeric sleeve 90. Yet another drive system, depicted in U.S Pat. No. 4,453,611, shows a drive wheel assembly 31 which includes a drive sprocket 48 located between rims 46 and 47. A drive system, depicted in U.S. Pat. No. 3,738,714, shows a pair of drive sprocket wheels 90 used in conjunction with bearing wheels 92. Finally, there is a drive sprocket wheel, depicted in U.S. Pat. No. 3,597,018, which includes an outer ring of one material for engaging an endless belt and an inner ring of natural or synthetic elastomeric resin for absorbing shocks that the endless belt may encounter. These examples of prior art drive wheel assemblies illustrate the fact that there is a need for a drive wheel assembly as taught by the instant invention.